using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;

namespace Modbus.Data
{
	/// <summary>
	/// A 1 origin collection represetative of the Modbus Data Model.
	/// </summary>
	public class ModbusDataCollection<TData> : Collection<TData>
	{
		private bool _allowZeroElement = true;

		/// <summary>
		/// Initializes a new instance of the <see cref="ModbusDataCollection&lt;TData&gt;"/> class.
		/// </summary>
		public ModbusDataCollection()
		{
			AddDefault(this);
			_allowZeroElement = false;
		}

		/// <summary>
		/// Initializes a new instance of the <see cref="ModbusDataCollection&lt;TData&gt;"/> class.
		/// </summary>
		/// <param name="data">The data.</param>
		public ModbusDataCollection(params TData[] data)
			: this((IList<TData>) data)
		{
		}

		/// <summary>
		/// Initializes a new instance of the <see cref="ModbusDataCollection&lt;TData&gt;"/> class.
		/// </summary>
		/// <param name="data">The data.</param>
		public ModbusDataCollection(IList<TData> data)
			: base(AddDefault(data.IsReadOnly ? new List<TData>(data) : data))
		{
			_allowZeroElement = false;
		}

		internal ModbusDataType ModbusDataType { get; set; }

		/// <summary>
		/// Inserts an element into the <see cref="T:System.Collections.ObjectModel.Collection`1"></see> at the specified index.
		/// </summary>
		/// <param name="index">The zero-based index at which item should be inserted.</param>
		/// <param name="item">The object to insert. The value can be null for reference types.</param>
		/// <exception cref="T:System.ArgumentOutOfRangeException">index is less than zero.-or-index is greater than <see cref="P:System.Collections.ObjectModel.Collection`1.Count"></see>.</exception>
		protected override void InsertItem(int index, TData item)
		{
			if (!_allowZeroElement && index == 0)
				throw new ArgumentOutOfRangeException("index", "0 is not a valid address for a Modbus data collection.");

			base.InsertItem(index, item);
		}

		/// <summary>
		/// Replaces the element at the specified index.
		/// </summary>
		/// <param name="index">The zero-based index of the element to replace.</param>
		/// <param name="item">The new value for the element at the specified index. The value can be null for reference types.</param>
		/// <exception cref="T:System.ArgumentOutOfRangeException">index is less than zero.-or-index is greater than <see cref="P:System.Collections.ObjectModel.Collection`1.Count"></see>.</exception>
		protected override void SetItem(int index, TData item)
		{
			if (index == 0)
				throw new ArgumentOutOfRangeException("index", "0 is not a valid address for a Modbus data collection.");

			base.SetItem(index, item);
		}

		/// <summary>
		/// Removes the element at the specified index of the <see cref="T:System.Collections.ObjectModel.Collection`1"></see>.
		/// </summary>
		/// <param name="index">The zero-based index of the element to remove.</param>
		/// <exception cref="T:System.ArgumentOutOfRangeException">index is less than zero.-or-index is equal to or greater than <see cref="P:System.Collections.ObjectModel.Collection`1.Count"></see>.</exception>
		protected override void RemoveItem(int index)
		{
			if (index == 0)
				throw new ArgumentOutOfRangeException("index", "0 is not a valid address for a Modbus data collection.");

			base.RemoveItem(index);
		}

		/// <summary>
		/// Removes all elements from the <see cref="T:System.Collections.ObjectModel.Collection`1"></see>.
		/// </summary>
		protected override void ClearItems()
		{
			_allowZeroElement = true;
			base.ClearItems();
			AddDefault(this);
			_allowZeroElement = false;
		}

		/// <summary>
		/// Adds a default element to the collection.
		/// </summary>
		/// <param name="data">The data.</param>
		internal static IList<TData> AddDefault(IList<TData> data)
		{
			data.Insert(0, default(TData));
			return data;
		}
	}
}
